Floating-venturi carburetor



Nov. 27, 1928.

C. L. RAYFEELD FLOATING VENTURI CARBURETQR 1920 5 Sheets-Sheet Filed Sept. 15

CA m Nov. 27, 1928, 1,693,350

C. L. RAYFIELD FLOATING VENTURI CARBURETOR Filed p 15, 1920 5 Sheets-Sheet 2 5 Sheets-Sheet IIIIIIIIIII C. L. RAYFIELD FLOATING VENTURI CARBURETOI Filed Sept. 15

Nov. 27, 1928.

Nov. 27, 1928.

C. L. RAYFIELD FLOATING VENTURI CARBURETOR Filed Sept- 15, 1920 5 Sheets-Sheet 4 F/ELU GA 2455 A. 8/7 "x 1 I Nov. 27, 1928.

c. L. RAYFIELD FLOATING VENTURI CARBURETOR F l p l5, 1920 s Sheets-Sheet 5 MW cu \Patented Nov. 27, 1928.

CHARLES L..BAYFIELD, OF CHICAGO, ILLINOIS,

TO MARVEL CARBUREIER COMPANY,

INDIANA.

FLOATING-VENT ASSIGNOR, BY MESNE ASSIGNMENTS,

OF FLINT, MICHIGAN, A CORPORATION OF URI oAnBnRE'roR.

dpplication filed. September 15, 1920. Serial No 410,403.

This invention relates to a carburetor, and particularly to a carburetor wherein the Vent-uri mixing chamber is automatically adjustable in such a manner that the proper fuel mixture is at ali times supplied to the engine on which the carburetor is mounted.

.In the design of carburetors, fuel economy andsmoothness of operation are features which must be given paramount consideration. These results are obtained by mixing the fuel and air in such proportions in the carburetor that a maximum explosive effort is produced when the mixture is ignited in the engine cylinder. Varying conditions of load and feed, however, require that the proportions and quantities of fuel mixture be constantly varied.

It is therefore desirable that a carburetor be provided which will supply the proper uantities of fuel mixture for varying conilitions of feed and load and that it be automatically adjustable to supply this mixture promptly and in sufficient quantities as the demand therefor arises. It is an object of this invention to provide a carburetor having a plurality of throttle controlled mixture adjusting means.

It is alsoan object of this invention to -provide acarburetor having throttle controlled mixture adjusting means and having suction controlled mixture adjusting means associated with certain of said throttle controlled means.

'It-isa further object of this invention to provide a carburetor having fuel injecting means adapted to be brought into operation by the opening of the throttle thereof.

It is an important objectof this invention to provide a carburetor having a plurality of nozzles certain of which are brought into op eration by opening the throttle ofthe car- -burctor.

It is also an important object of this invention to provide a carburetor having a casiug affording a Vcnturi mixing chamber, said casing being movable to admit additional fuel mixture on the outside thereof.

. It is finally an important object of this invention to provide a carburetor having a plurality of coacting throttle controlled and suction operated means for varying the fuel mixture. d

Other and further important objects of this The invention (in a preferred form) is shown on the drawings and hereinafter more fully described.

On the drawings:

Figure 1 is a side elevation 'of a carburetor embodying the principles of this invention.

Figure 2 is an elevation thereof. a

Figure 3 is an end elevation. Figure 4 is a section on the line 4-4 of Figure 3.

Figure 5 is a plan view.

Figure 6 is a section on the line 6-6 of Figure 5.

- Figure 7 is an enlarged fragmentary section on the line 7Z of Figure 2.

Figure 8 is a section on the line 88 of Figure 2. I

Figure 9 is an enlarged fragmentary section on the line 9-9 of Figure 4. v

Figure 10 is an enlarged fragmentary section on the line 10-10 of Figure 4.

Figure 11 is a slightly enlarged section on the line 11-11 of Figure 6.

Figure 12 is an enlarged fragmentary section on the line 1 212 of Figure 6.

Figure 13 is'an enlarged'fragmentary detail section ofthe liquid fuel inlet.

Figure 14 is a fragmentary vertical section through the liquid dash-pot chamber and the piston operating therein.

Figure 15 is an enlarged section on the line 1515 of Figure 14.

Figure 16 is an enlarged fragmentary section with parts in elevation on the line 1616 of Figure 5.

As shown in the drawings:

The carburetor of this invention comprises in general a unitary casing in which is formed of the opposite side a. float or fuel supply chamber 1, an air inletpassage 2 and a mlxing chamber 3, the ,outlet of fuel from which is controlled by a butterfly throttle valve 4. As shown in Figures 6 and 13. liquid fuel enters the chamber 1, through a chambered boss 5, to which a pipe from the source of fuel extends, through a passage in I the bottom of the casing from which the supply chamber is formed, and into said chamber 1 through passages 6 in a hexagonal nut 7,

mounted in said cylindrical well 17.

which is an integral part of a plug 8 engaged in the passage in the casing. A needle valve 9, in ihe passage in said plug 8, controls the flow of liquid fuel through the passages (3,

' naldiameter of the tube 11, thereby affording a passage between said tubes. A conneciion'between said passage 15 and the interior of the tube 1-1 is provided by the restricted passage 15. .For closing the upper end-0t tube 14 a metering pin 16 is provided and said metering pin is adapted to be moved outwardly in said tube to allow liquid fuel to be drawn therefrom, thereby providing an inner nozzle, An extension 16 on said metering pin 16 projects downwardly through the tube 14, into a well 17, which is formed in the carburetor casing directly beneath the air inlet passage 2, and said extension 16 is connected to a piston 18, which is slidablty 1 S shown in Fig. 14, said piston 18 is provided trim vertical passages 19 and with a check valve 20, which is loosely secured on the extension 16 of the metering pin 16, and by this arrangement said piston is adapted to move easily downward through the liquid in the well 17, but its upward movement therethrough is restricted since the check valve .20 closes over the passages 19 due to its weight. Slidably mounted in the carburetor casing above the air inletchambcr 2 is' a casing 22, in which is centrally formed a Venturi chamber 23 which surrounds the upper end of the stand pipe or tube 11. said casing 22 is provided with a plurality of outwardly extending fins 24, which are adapted to slidably engage the side of the carburetor casing and afi'ord a passage. between the casing '22 and the inside of the carburetor easing. An annular boss .25, which is formed on the outside of the casing 22, near the lower end thereof. is adapted to engage an annular tlangeuflt formed in the carburetor casing at the upper end of the air inlet chamber and thus closcthe connection v l from said air inlet chamber to the passages formed between the time .24 and the outside of the casing 2-2, and the inside of the carburetor casing. To restrict the entrance of air into the Venturi chamber 23, a double cone 27 is secured around the tube 11, adjacent the entrance to said chamber, as clearly shown in Figure (3. Said cone 1'27 may b made adjustable by internally threading the same and by threading the outside of the tube 11 to engage As shown in Figure 4, r

from the float chamber 1 through the same. It is apparent-from the preceding description that the. construction of this invention provides in etl'ect a floating vcnturi. Upon the pr duction of increased suction due to a high or increased engine speed, the casing 22 will be lifted upwardly and the boss. moved away from its seat on the flange 26, thus allowing an additional passage for the flow of air into the fuel outlet chamber-.3.

Means are provided whereby the metering pin 16 is moved upwardly in the. tube 14 by the. upward movement of the casing 22, therelrvathmtting-a certain quantity of additional fuel through-the inner nozzle when additional air is admitted around the casing For this purpose, inwardly extending arms 28 are provided near the upper end of the casing 22 and said arms extend to the center of the upper end of the Vcnturi chamber 23, where they are loosely engaged between flanges of an internally threaded boss 29, which is engaged on threads on the upper end of said metering pin 16. A plate ad ustably se cured on the pin 16 below the boss 29 deflects the fuel in its upward course and acts to thoroughly mix the same, adding to the economy of the'carburetor. Since said plate 30 moves away from the nozzle at high speeds and towards the same at lower speeds, the defleeting efi'ect; thereof is properly compensated. Thus it is apparent that an upward movementof the casing 22'is transmitted to the metering pin moving the same outwardly in the tube 14 and allowing fuel to flow thereast from the interior of said tube. Since the piston 18, which is movable in the liquid in the well 17, is connected to the lower end of said metering pin, the upward movement thereof with the. casing 22 is retarded by the resistance otTcred by the liquid in said well, while at thesame time. on account of the provision of the check valve 20 and the passages 19 in'the piston 18, the casing 22 and the metering pin are quickly dropped back into position when the suction which lifted the same upwardly ceases. In this connection, it is to be noted here that the upper end of the well 17 is closed by an outwardly extending flange 31. which is provided on the lower end of the tube 14.

Means are provided for supplying liquid fuel to the well 17 and to the interior of the tubes 11 and 14. For supplying the well 17' with liquid fuel, a passage is provided in the carburetor casing opening into said well and said passage communicates with another passage 33; which in turn communicates with a vertical passage 31, communicating with a well 35. which is supplied with liquid fuel a'passage 88, as clearly shown in Figure Said well with the vertical passage 34 leading therento is shown in Figure. 9. Liquid fuel is' supplied to the interior of the standpipe tube 11 by means of a passage'BG, which connects .the carburetor casing as clearly shown in Fig. 2, and the flow ofifuel theiefrom into the passages 34 and valves 43 and 44, which are slidably mounted in said passages and adapted-to be seated and the passageJOO and unseated by the closing and opening of the throttle ina manner which will now be described.

A passage 100 in the casing 42 affords an atmospheric connection to the top of the well and since the passage 89, which supplies liquid fuel thereto from the chamber 1, is restricted by an apertured nut 89, Fig. 7 the supply of liquid fuel will be drawn therefrom upon initial acceleration of the engine. After the exhaustion of the liquid fuel in said well 40 and during continued running at high speeds, air willof course be induced through supplied to the carburetor nozzle through the passage 36. Said well 40 will be again fillai with liquid fuel through the-restricted passage 89 upon stoppin or slowing down the engine.

Tie butterfly throttle valve 4 is secured on a shaft 45, which is pivoted transversely in the carburetor casing in the mixture outlet chamber 3 thereof in the usual and wellknown manner and on the outer end of said.

shaft 45 is secured an eccentric cam 46. which rotates with the shaft 45 when the throttle is opened or closed to contact with a roller 47 which is mounted on one end of a bell crank rocker arm 48, which is pivoted to the outside of the carburetor casing at 49. The other of the rockerarm 48 is bifurcated and extends outwardly to engage under a fork 50, which is provided with a threaded aperture to receive a. threaded portion 51 on the upper cnd'of the. needle. valve 43. Said fork is also adapted to contact a knurled nut 5'2,wh ich is secured to the upper end of the needle valve 44iand to lift said valve upwardly away from its seat when the throttle is moved into open position. It is to he noted, however. that the fork 50 acts to more the needle valve 43 at any time the rocker arm -15 is moved while the needle valve 44 is not moveduntil after considerable rocking move meut ,of said rocker arm has been effected. as for exam le, when the throttle is opened at half to tlireequarters o n position. Said knurled nut'52 also-provides means whereby the needle valve44 may be adjusted longitudinally in the casing-42. Means are alsoprovided for adjusting the needle valve 43 longitudinally and for this purpose a knuried nut 53 is secured to the upper end of said needle 39 is regulated by needle- 59 and a constant air port valve whereby the same may be rotated in its threaded aperture in the fork 50 to adjust its position relative to the fork 50. In order to lock said knurled nut 53 in adjusted position,

a spring-pressed detent 54 is provided and a similar spring-pressed detent may also be provided for locking the knurled nut 52 in adjusted position.

An auxiliary nozzle is provided for supplying at' all times a limited amount of fuel mixed with air to the mixing chamber 3 from a point above the annular flange 26. For this purpose a passage55 leading into the'well 35 conducts liquid fuel to awell 56 formed in a casing 57 on the same side of the carburetor casing as the rocker arm 48. Mounted in the upper end of said well 56 is a. restricted nozzle 58 in the casing 57 supplies air to the fuel leaving the upper end of said nozzle. The auxiliary nozzle serves to supply a substantial iy uniform quantity of fuel. sullicient to form a pioperly explosive mixture with the air flowing through the venturi when the venturi is seated on the flange 26.

In order to for a supply of fuel plying fuel mixture to the mixing chamber 3 at a point posterior to the throttle valve 4. This arrangement is shown in Figures 1, 3 and 16 and comprises a casing 60, which is provided with a plurality of passages which provide for easy starting and mlxture when the engine is idlin' an arran ement is rovided for suwhich a valve 68 is rotatablv mounted for selcctively connecting said chamber (37 either with said passage 66 or with the atmosphere through a vertical passage 69 leading from said cylindrical chamber. Leading upwardly from the cylindrical chamber 67 is a passage 70 which opens into a passage 72 in a casing 71 which is secured to the top of the main cas-' ing and which is provided with an aperture 73 into which the plug 64 extends. For regulating the flow ofair or fuel through said passage 72, a valve 74 is engaged in the outer end thereof and is adapted to he adjusted therein by rotating a threaded portion 75 thereon in a threadedportion 76 of the casing- 71. rotating said valve 74, the outer threaded portion 75 is provided witha knurled head 77, as clearly shown in Figures 1 and 16. Thus it is apparent that fuel the passage 65 in the plug 64 is mixed witliair from the passage 70 in the passage 72,,the valve 74 being cut away as shown to allow free passage of this mixture thereabout and For end of the leaving from th is passage 72 the fuel mixture is drawn upwardly through a passage 78 into a c1rcular passage 79, which is formed between a bushing 80 surrounding the throttle shaft 45 above the throttle valve 4. Thus provision made for supplying mixture to run the engin it My when the throttle valve 4 is in closed position. I v

In order to facilitate starting, means are provided whereby a very rich mi'xture may be introduced throughthe passage 82. T0 at) eomplish this result the cylindrical valve 8 is rotated so that .the air inlet passage 69 is closed and so that the chamber only \vi th the liquid fuel passage 62. In order that said valve (38 may sired position for starting the engine or for running idle, an extension 83 thereof is brought outwardly through the casing (30 and a lever St is non-rotatably secured to the outer end of said extension. Said lever 84 is pro-, vided with a binding post 85, whereby a rod or Bowden wire may be attached thereto so that the lever may be operated from a distance to rotate the valve 68. An extension 86 is provided on the end of said lever 84: opposite the binding post and a stop 87 which is adapted to be en aged by said c'XtensiouSG and by the lever 84 said lever in both directions so that it is possible to readily ascertain when the valve (38 is rotated into the desired position. .7

Any suitable means may be provided for rotating the throttle shaft 45, such as a rocker arm 90, as shown in Figure 3.

The operation is as tollowsz" The float chamber is filled with liquid fuel which enters the same through the boss 5 and the level in said float chamber is maintained in the usual manner by the action of the. float 10, and the needle valye 9 controlled thereby. \Vhen it is desired to start the engine, the

1ever 84 is actuated to rotate the. valve (38 in such a manner that the air passage 6918 closed and consequently a very rich mixture or practically raw fuel is drawn into the mixing chamber 3, above the throttle 4. After the engine has started the lever 84 is of coursev moved back to its original position so that the liquid fuel passage 66 iselosed and the air passage 69 is again opened and a properly proportioned mixture of air and liquid fuel enters through the passage 82. This mixture, which is introduced through the passage 82, sutiices to idle the engine when the throttle valve is closed and the operation of the carbn'retor which takcsplace upon opening said throttle valve will now be described.

Upbn opening of the throttle the nozzle 59. which is supplied with air from the constant air inlet 58, supplies'prhnary mixture to the allowed to (low' into the well 17 through said well 17 rises 7 2 is connected be rotated into the de- .14, and therefore the amount of fuel limits the movement of throttle shaft- {15 to contact with the roller -17 and to rock the rocker arm 48 about the pivot 49 whereby the needle valve 43 is lifted from its seat, and the additional fuel required 11s t to passages 34 33 and 32. The valve 43 issuificiently opened at all times to allow a limited low of fuel into the well 17. The fuel fron upwardly inside the tube ll and is drawn out throughv the apertures 13' int'o the Venturi chamber "23, where it is mixed with air from the air inlet chamber Said fuel which is drawn into themixing chamber through the apertured passages 13 enters'the chamber 15 between tubes 11 and 14 through a restricted passage 15 formed in the tube -drawu through said aperture is limited. As the speed of the engine increases the suction produced thereby lifts the casing 22 so that the. boss 25 thereon is lifted away from the flange .26 and additional air from the air inlet chamher .2 is drawn upwardly between thelins 24 on said casin g 22. This upward movement of the casing moves the entrance to the Von turi chamber 23 away from the cone '2? and consequently increases the size'of the op ning thereinto and increases the amount of air which may be, drawn therethrough. On account of the action of'the piston 18 in the well 17, this upward movement of the casing 22 is a gradual one so that the acceleration of the engine effected thereby is smooth and steady. The additional air which is int roduced by the lifting of the casing 22 requires additional fuel and this is provided for by the outward moweinent of the metering pin 16 in the tube 14:, which permits liquid fuel to be drawn from said tube. This action, however, is a compensating one and prevents the loading efi'ect often caused by such con-- ditions.

Means are also provided for introducing additional fuel at high speed or when the throttle is in open position. After the throt tle has been moved to about half to three quarters open position. the fork 50 has been lifted by the rocker arm 48 sutficicntly to contact with the. bottom of the knurled nut 52 on the needle valve 44,-raising the same from its seat in the bottom of the \\'cll-l0 and momentarily supplying additional liquid fuel to the chamber-15 through the passages 39. 3 37 and 36. After the exhaustion of the fuel in the well 40, air is induced through the passage into said passages. T has at high speed there are a. plurality of jets in opera-- .tion. Fuel is supplied through the apertures nmg conditions.

nozzle 6.4.' On account of the sliding movement of the casing 22, the proper amountof air is supplied at all times and the compensating movcmen of the casing 22, together with the throttle controlled liquid fuel supply, provides an arrangement whereby the proper fuel mixture is promptly supplied foroall run- On account of the provision ofthe check valve 20 the casing 22 is allowed to drop quickly back so that the boss 25 thereon seats on the flange 26 when the speed is diminished and the suction ceases. Thus while the upward movement of said casing isgradual by the action of the piston 19, there is no lag in its movement back to normal position upon cessation of suctio p.

Adjustments which may be necessary for the proper proportioning of the fuel mi xti: re may conveniently be made. Adjustment of the needle valves 43 and 44 is effected by rotating the knurled nuts 52 and 53, adjustment of the air supply through the nozzle 64 is effected by rotating the knurled nut 77, and adjustment of the air inlet into the Venturi chamber 23 is ordinarily made when the carburetor is assembled by adjusting the double cone 27 longitudinally on the sleeve 11.

As is apparent from the foregoing description, the carburetor of this invention provides means wherebya properly proportioned mixmade smooth and ture is supplied to the engine under all running. conditions and means whereby this miX- ture is compensatingly proportioned by means dependent both uponsuc tion and upon the amount of throttle opening.

I am aware that numerous details of construction may be varied through a wide range without departing from the principles of this invention, and I therefore do not purpose limiting the patent granted otherwise than necessitated by the prior art.

I claim as my invention:

1. In a carburetor, a plurality of wells communicating therewith, a compound nozzle communicating with said wells, means for controlling the flow of fuel from said wells to the nozzle, and throttle controlled means for successively operating, said controlling means.

2. In a carburetor, a fuel supply chamber, a plurality of wells communicating therewith, a compound nozzle, :1 separate communication from each of said wells to the nozzle, and

throttle controlled means in each of said wells,

said means successively controlling the flow of fuel therefrom to the nozzle.

In testimony whereof I have hereunto subscribed my name.

CHARLES. L. RAYFIELD.

a fuel supply chamber, 

